Method of making anhydrous magnesium chlorides



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P. COTTRINGER ET AL METHOD OF MAKING ANHYDROUS MAGNESIUM CHLORIDES IFiled April 1, 1921 2 Sheets-Sheet 1 ATTORNEYS P. COTTRINGER ET ALMETHOD OF MAKING ANHYDROUS MAGNESIUM CHL ORIDES Dec. 29 1925- ,3 7

t Filed April 1, 19'21 2 Sheets-Sheet 2 i" I v $2) I FUEL QU'PPLY $444K,I

w Y w 0 INVENTOR5 Paar] @firz'uger and 7 BY Uzi/[a222 R Col/1 2235 96L%v Q A TTORNE 6.

Patented Dec. 29, 1925.

.YYUNITED srArs-s PATENT OFFICE.

raur. corrnmean AND WILLIAM R. commas, or mnnami, memoir, assrcnons TOTHE now CHEMICAL com any, or MIDLAND, mcmom, a conrona'rron or mrcmonr.1 a

Ma r-non or mama amrrnaous MAGNESIUM cnnoamns.

Application filed April 1,1921 Serial No. 457,611.

T all whom it hwy-concern: Y Beit known that we, PAUL OOTTRINGER andVILLIAM R. CoLLINcs, citizens of the United States, and residents ofMidland, 6 county of Midland, and State of Michigan, f have'invented anew and useful Improvement in Methods of Making Anhydrous MagnesiumChlorides, of which the following is a specification, the principle-ofthe in- 1 vention being herein explained and the best mode in which wehave contemplated applying thatprinciple, so as to distinguish it fromother inventions.

So far as we are aware, in all methods heretofore proposed for thedehydration of magnesium chloride, such dehydration has 7 i beeneffected by passing either a current of airor equivalent gases at theproper temperature over the hydrated salt, or else by si-'multaneouslytpassing over such salt a cur-- rentof drylhydrochloric acidgas. It has not beenfound possible to completely dehydrate the salt inthepresence of air alone,

' and" an atmosphere of hydrochloric acid gas has necessarily beenemployed, at least in all commercial processes, foneflecting the finaldehydration; To employ such gas, however, for the whole operation isobviously not fea- 'sible because of the quantity of dilute hydroaochloric acid that would result, and the process most generally favoredaccordingly has been one. wherein the double magnesium-ammonium salt isformed by adding ammonium chloride to a solution of mag-' 36nesiumchloride, then evaporating to dryne'ss, carefully heating andfinally igniting. Thedifiiculty with heating the normal hexa-hydrate(MgCl .6H O) either directly or by passing a current of heated airthere- 40 over, 1s that such hydrate Will melt and form a solution inits water of crystallization at'a relatively low temperature anddehydration of the resulting solution must be carried on at avery'slight increase of 4-5 temperature and with extreme cautlon 1fdecom osition of. the salt is to be avoided.

T e object of the present invention is to provide an improved method andapparatus for use therein whereby the partial dehydration of the salt inquestion (down to the stage where final dehydration by means of a streamof hydrochloric acid gas may be economically employed) may beaccompllshed without encountering the difficulty 3ust noted. At the sametime such dehy- 5 dratlon, for example to the dihydrate form, is quicklyand economically effected, the apparatus requiring a relatively smallamount of floor space and a minimum of oversight and attention while inoperation. To the accomplishment ofthe foregoing and related ends theinvention then consists of the steps and means hereinafter fullydescribed and particularly pointed out in the claims, the annexeddrawing and the followmg description setting 'forth, in detail one modeof carrying out the invention, such disclosed mode constituting,however, but one of various ways in which the principle of the inventionmay be used.

In said annexed drawing: a Fig. 1 is a plan View of one form of ap--paratus adapted for carrying out our present improved method or process;Fig. 2 is an end elevation ofthe same; Fig. 3 is a side elevationthereof; and Figs. l and 5 are vertical sections taken on the planesindicated bydtlge lines 4-4 and 55 on Figs. 1, 2 an Briefly stated, thepresent improved processconsis'ts in drying to the stage indicated asolution ofthe normal hexa-hydrate salt on the surface of a rotary drumdryer, such solution consisting either of the salt in quest iondissolved in its own water of crystallization, or with a slight excessofwater, it being unnecessary for use in the process in hand that thesalt be first crystallized out as in prevailing methods. i

Referring to the several figures of th drawing,. the drum 1 is providedwith trunnions journaled in suitable bearings 2, said drum being closedsave for inlet and outlet openings through such trunnions respectively.Located below the drum is a suitable receptacle 3 into which thelowermost portion of the surface of the drum dips, a suitable quantityof the aforesaid solution of normal hydrate being maintained in saidreceptacle so as to kee the level thereof substantially constant. hedrum as shown will contact with the solution in the receptacle, and inaddition, or without such contact, a rotary brush 4 may be providedwhich best shown in'Fig.

dips into the solution and also contacts with the surface of the drum,thus insuring the adherence of a-film of such solution to the surface ofthe drum as the latter rotates in the direction indicated by the arrow.,Rotation of the drum and of the brush is provided for by means ofsuitable driving -meehanism consisting of a train of gears 5 which doesnot need to be described in detail. On the opposite side of the drumfrom receptacle 3 there is located an adjustable scraper 6 that may bepressed into more or less close contact with the surface of the drum bymeans of handwheel 7, as will be readily understood, and serves toscrape off the film in question which in the meantime will have become athin, dry layer of the partially dehydrated salt, as will be presentlyexplained. A chute or suitable receptacle (not shown) will ofcourseprovided to receive the material as it is communicate .with the housing.on the respective sides of said drum and on a horizontal plane passingthrough the latters axis (see Fig. 2). Extending into the other hollowtrunnion of the drum is an oil or gas burner 12, the gases ofcombination from which are discharged directly into the interior of thedrum, their uniform distribution .being effected by means of a hood orbaffle 13,

disposed to initially direct such gases in a downward direction. Thetemperature of the surface of the drum is maintained by the foregoingmeans at from between 250 degrees to 350 degrees centigrade, and afterpassing through the drum, the gases of combustion, it will be observed,may be returned by means of the branched duct 11- to the housing 10,where they pass over the drum and in direct contact with the film ofmaterial thereon before finally escaping. In this way the processishelped out not only because some of the moisture is carried off I withthe gases but heat losses due to radiation from the drum are at the sametime out down, the products of combustion, to-

gether with the water vapor and any slight amount of hydrochloric acidgas that is set free, passing up the stack together.

By keeping the temperature of the drum surface within the rangeindicated and by properlyregulating its rate of rotation so that thefilm of chloride that adheres to such surface is in contact therewithfor approximately one minute, we have found it possible to completelydry the normal hydrate (MgGl fiH O) to the dihydrate form (MgCl 2I-I O).There will be a slightly greater lossby decomposition of magnesium.

chloride to the oxide with corresponding setting free of hydrochloricacid than where the drying is carried on by bringing heated aironly intocontact with the chloride, but the method has not only the advantage ofmuch higher'rate of drying but the normal chloride which forms thestarting material does not have to be crystallized ,or flakedpreliminary. to such drying operation. Moreover a minium of floor spaceis required by the a paratus because of its compact design an the fuelconsumption should not be. any greater, if asgreat as in a process Whereheated air alone is relied on to effect dehydration.-

It will be understood .of course that instead of either the fusedhexa-hydrate or a solution thereof forming the starting material, anylower hydrate that will stay molten at the elevated temperature to whichit is subjected due to contact of the drum with the material inreceptacle 3, may be used, The product from the apparatus which willconsist in the main, as ust stated, of the dihydrate, wherethetemperature and other.

controlling factors are properly determined, may then be completelydehydrated in the chloric acid gas in a suitable a paratusu As bestshown in Fig. 1, t e branched duct 11 is also provided with a straightex-' tension 15 controlled by a suitable valve or damper 16; also asimilar valve or damper 17 is placed in each of the branches of saidduct 11. By virtue of this arrangement, the ases of combustion may, ifdesired, be conned wholly to the interior of the drum 1, beingdischarged directly therefrom through such extension 15; or such gasesmay be returned in whole or part through such branches of duct 11. Thevalves or dam ers 17 in such branches, morrsver, may

adjusted in different open positions to varythe heating effect of thegases as applied to the respective portion of the drums cylindricalsurface lying on opposite sides of a vertical plane I passing throughthe axis of the drum. The heatin intensity of the two currents of gasest us passed over such respective film portions .is of course a functionnot merely of the temper ature of the gases, which will be approxi-'mately the same at least initially in the case of both currents, butalso of the rate of- In a flow and volume of the two currents. otherwords, by reducing the rate of flow or volume of the current onone sidebelow usual way by employing a current of hydroour invention may that onthe other side, a corresponding dif- 'ference in rate of dryin and ineffective heat application. to the m is obtainable. Other modes ofapplying the rinciple of e employe instead of the one explained,change'being made as regards the steps herein disclosed, provided thosestated by any of the following claims ,ortheir equivalents be employed.

' We therefore particularly point out and distinctly claim as ourinvention 1. In a method of treating liquefiable chemical compounds, thesteps which consist in bringing successive portions of the exteriorcylindrical surface of an interiorly heated rotary drum into contactwith a liquid body'of such a compound, whereby a film of the latter iscaused to adhere to such gases of combustion aving different degrees ofheating intensity over the portlons of such film lying on opposite sidesof a vertical plane passing through the axis of such drum, and thenremoving such film.

2. In a method of removing water from chemical compounds, the stepswhich consist in bringing successive portions of the exteriorcylindrical surface of an interiorly heated rotary drum into contactwith a liquid body of such a compound, whereby a film. of the latter iscaused to adhere to such surface, simultaneously passing currents ofgases of combustion having different deg grees of heating intensity overthe portions of such film lying on opposite sides of a vertical planepassing through the axis of such drum, and then removing such film.

3. In a method of removing water of crys- 1 tallization from a hydratedform of ma nesium chloride, the steps which consist in bringingsuccessive portlons of the exterior cylindrical surface of an interiorlyheated rotary drum into contact with a liquid body of such chloride,whereby a film of the latter is caused to adhere to such surface,simultaneously assing currents of gases of combustion having differentdegrees of heating intensity over the portions of such film lying onopposite sides of a vertical plane passing through the axis of'suchdrum, the hotter gases being passed over the film portion that hastraveled farthest from the point where the drum contacts with suchliquid body, and then removing such film after such chloride has beensuitably dehydrated.

- 4. In a method of removing water of crystallization from a hydratedform of ringing successive portions of the exterior cylindrical surfaceof a rotary drum into contact with aliquid body of said chloride,whereby a film of the latter is magnesium chloride, the steps whichconsist surface, simultaneousl passing currents of 1n caused-to adhereto such surface, applying heated gases of combustion interiorly to saiddrum, simultaneously returning such gases of combustion after passingthrough the drum to contact with such cylindrical surface of said drumon opposite sides of a vertical plane passing through the axis thereof,the return of such gases being regulated so that the hotter gases arepassed over the portion of such drum-surface that has traveled farthestfrom the point where such surface contacts with such liquid body, andthen removing such film after said chloride has been suitablydehydrated.

Signed by us, this 25th day of March, 921.

PAUL COTTRIN GER. WILLIAM R. COLLIN GS.

